decca tree microphones

[richgilb]

Almost every time decca trees get mentioned in a thread, there is usually someone that points out that you should only use omni mics that become increasingly directional higher up the frequency range. Then this point never seems to get fully developed or challenged by people that have tried it with AND without these types of mic.

1.Does anybody out there have exeperience of trying it both ways?
2.Why does a decca tree lend itself to this kind of mic? Is it because the stereo imagery becomes blurred in a decca tree and more driection at high frequencies compensates for this by placing some of the instruments?
3. If I am right in 2,would using a 'decca tree' mic be too focussed when used as a stereo pair?

Thanks in advance for your insights....

Rich

[rumleymusic]

2.Why does a decca tree lend itself to this kind of mic? Is it because the stereo imagery becomes blurred in a decca tree and more driection at high frequencies compensates for this by placing some of the instruments?

That is probably part of it. Directional high frequencies also diminish the phase problems that occur when using spaced omnis, especially when one is summed to both channels equally.

3. If I am right in 2,would using a 'decca tree' mic be too focussed when used as a stereo pair?

The Neumann M50 makes a fantastic stereo pair mic. You just have to be careful not to space them too far apart and be sure to angle them appropriately. I have recorded in a hall with permanent omnis with APE's spaced about 3ft with a 90 degree angle. I definitely hear a gap in the center. You can't always treat highly "directional" omnis like a standard omni.

Sorry, can't comment on No. 1

[fifthcircle]

I've tried trees with all sorts of mics over the years. Some definitely work better than others.

What it comes down to is this (in a simplification):

You are recording with what is basically a spaced mic array (not unlike A-B or other similar patterns). Your left and right are likely to have a hole in the center which is where the center comes in.

Omnis are not exactly known for imaging. You get a lot good stuff out of them, but a good image usually isn't one of them. Using balls or a mic with the increasing directionality helps focus the sound in the image. You can certainly use a basic omni on a tree, but I have found that the lack of focus and dig into the group can be a problem. Using the balls (in my case 50mm balls on DPA 4006 mics) really helps the sound "snap" into place. Part of it is phase relationships (as Rumley mentioned), but it is more than that... The pickup itself has a bit more space without overlapping pickups. The differences in pickup of those mics helps make the tree work.

Hope this makes sense...

--Ben

[richgilb]

Ok, so if omnis are not so good at imaging, and mics with increased direction at high frequencies help in a decca tree, why do people only point out that you need this kind of mic in a decca tree? Surely a spaced pair would also be better off using an M50 kind of mic? Or does this go back to my theory that the 3rd mic in the tree can blur the already subtle imaging of a spaced omni pair?

[7rojo7]

The center mic is usually at a lower volume than the outer mics, usually dialed in by ear.
I've used CCM21 in a DECCA like formation and CCM5 (they have some HF directivety in their omni setting, or maybe it's just an overall HF rise) There's a more natural LF response from the CCM5 in omni, you can be further from the source, you must be closer with the CCM21 or it starts to sound 'honky'. I've tried the 21 as the outer mics and a 5 as the center mic in omni and flankers in cardiod, pinged and time aligned in post (this worked the best IMO)
All of your questions can be answered 'it depends on where you put them' and that depends on what your orchestra seating plan is, what your recording space sounds like and what your placement limitations are.

[JonesH]

Originally Posted by richgilb

Surely a spaced pair would also be better off using an M50 kind of mic?

Sure it can. On the other hand you lessen the common signal so at the same distance you probably get more hole in the middle with directional mics. A 4006 with 50mm APE is almost a 4015 sub-cardioid with pressure-mic characteristics, directionwise.

Originally Posted by 7rojo7

There's a more natural LF response from the CCM5 in omni, you can be further from the source, you must be closer with the CCM21 or it starts to sound 'honky'. I've tried the 21 as the outer mics and a 5 as the center mic in omni and flankers in cardiod, pinged and time aligned in post (this worked the best IMO)

Interesting. Moving closer with the more directional ccm21's would also give you a closer sound I take it? I'd have guessed you'd move them further away compared to the omnis to get the same direct-to-room ratio.
Also interesting that you found it best to time align the center mic (if I read you correctly). One of the things that the center mic does is that it receives the sound before the LR mics and in that way helps with image stabilization (a haas-related thing I suppose.). If we didn't want the time delay we could simply use ABC-stereo and have them all in a row.

I should try with and without time-alignment.

[rumleymusic]

Also interesting that you found it best to time align the center mic (if I read you correctly)

I think he means time aligning the cardioid flankers. You are right, delaying the center mic would negate all the positive effects of the tree.

[JonesH]

Originally Posted by rumleymusic

I think he means time aligning the cardioid flankers. You are right, delaying the center mic would negate all the positive effects of the tree.

Ah, that makes more sense... Flankers = outriggers?

[telejustin]

Okay, so here's why I think everyone loves the spherical capsule/changing polar pattern thing on decca trees: since the mics are more directional at higher frequencies, you get the imaging of using cardioids (more pinpoint, less smearing and therefore more exciting & interesting recording) but the mic also captures the lower frequencies of the room sound (less first reflections) as it becomes more omni at lower frequencies. Basically, you're capturing the warm room sound whereas regular omnis would be getting a more broadband room sound that can be less musical.

Plus, you get the added bonus of a mic that's very linear down to 6hz or something stupid, so when the basses and drums come in rocking you capture that bottom octave nicely.

Hopefully that explanation helps with why everyone loves those. Or why I think so at least.

As for alternatives, I've used pretty much every conceivable thing on a tree. M50/M150's are definitely the bomb, but other things can be way cool too. IMHO, it's highly dependent on the room.

In super reverberant rooms (or crappy sounding rooms/festival tents) I've tried mics with tighter patterns to get less room sound, or in situations where I couldn't get the mics exactly where I wanted. In a studio or drier space, omni's or spherical capsules are the way to go.

2 ideas:

1. Cardioids on the tree, then add omni outriggers/flanks to the far sides of the orchestra. Gives you some juice and a little more room sound and low end, plus wider image which I like. Just be careful of phase with the tree. Use mics back in the hall pointed away from the stage to capture the room sound (reverb return). Blend to taste.

2. Use omnis or whatever you want on the left and right of the tree, and then use a stereo pair in the center. Yes I said stereo pair. Try an M/S pair and you can make the middle as wide or narrow as you want. Or do an x/y pair and you'll get all of the woodwinds nicely. Coincident here is more important so you have fewer phase cues and possible smearing.

PS: Sub cardioid's are cool, too! I did a whole season with an orchestra using MKH-800's in subcardioid on a tree.

JP

[JonesH]

Originally Posted by telejustin

2. Use omnis or whatever you want on the left and right of the tree, and then use a stereo pair in the center. Yes I said stereo pair. Try an M/S pair and you can make the middle as wide or narrow as you want. Or do an x/y pair and you'll get all of the woodwinds nicely. Coincident here is more important so you have fewer phase cues and possible smearing.
JP

Yes, that's something Ron Streicher is famous for. At least where I come from, this twist is usually called Decca á la Streicher.

[richgilb]

Anyone tried the Blue Bottle Rocket with B4 capsules in a decca tree?

[Nobilmente]

Originally Posted by telejustin

2. Use omnis or whatever you want on the left and right of the tree, and then use a stereo pair in the center. Yes I said stereo pair. Try an M/S pair and you can make the middle as wide or narrow as you want. Or do an x/y pair and you'll get all of the woodwinds nicely. Coincident here is more important so you have fewer phase cues and possible smearing.
JP

Originally Posted by JonesH

Yes, that's something Ron Streicher is famous for. At least where I come from, this twist is usually called Decca á la Streicher.

We usually call it - stereo pair flanked by omnis !!!!

[klaukholm]

Originally Posted by JonesH

A 4006 with 50mm APE is almost a 4015 sub-cardioid with pressure-mic characteristics, directionwise.

I disagree.
I just got done mixing a CD where the tree had a double setup of wide cardioids and M150. The patterns come across very differently.
The bass is a lot drier and tighter in the wides, and even in the mids there is less room.

[JonesH]

Originally Posted by klaukholm

I disagree.
I just got done mixing a CD where the tree had a double setup of wide cardioids and M150. The patterns come across very differently.
The bass is a lot drier and tighter in the wides, and even in the mids there is less room.

Then I agree with you, Kjetil - real-world experience trumps spec-reading any day of the week

I see that trying to recall spec sheets from my mind failed me this time; 4015 and 4006+ape are quite a bit different (of course, never said they were the same, but...). In the absolute treble it's somewhat similar, but the 4015 is much more directional (and of course lacks the treble rise of the APE-equipped mic.

[Yannick]

Alternatively, you can use SF1 on the sides, and a SF12 in the center (as MS).
We've had some nice results with that.